Backplate latch for machine guns



May 9 A. ANDERSON 2,441,382

BACK PLATE LATCH FOR MACHINE GUNS Filed May 25, 1945 W Am I 46 f 43 L L 5k 42 I L///// 40- A8 43 g .5

AW "5 MMIINVENTOR.

Patented May 11, 1948 BACKPLATE LATCH FOR MACHINE GUNS Louis A. Anderson, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a

corporation of Delaware Application May 25, 1945, Serial No. 595,671

9 Claims.

This invention relates to ordnance and more particularly to an improved back plate latch for machine guns.

It is an object of this invention to provide an improved safety means for preventing accidental operation of the latch which holds the back plate of the machine gun in place.

A further object of this invention is to simplify the latch mechanism.

Another object of this invention is to provide a safety means which may be changed over from right-hand operation to left-hand operation with a minimum amount of effort and inconvenience.

A further object of this invention is to reduce the cost of the latch mechanism.

A still further object of this invention is to provide a latch mechanism which includes a safety device which is unaffected by the jarring action resulting from the firing of the gun.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a fragmentary plan view of the breech end of a machine gun;

' Fig. 2 is a side view, with parts broken away. of an end plate showing the relationship of the safety mechanism to the latch element;

Fig. 3 is a rear view, with parts broken away, showing the manner in which the safety plunger is supported within the end plate;

Fig. 4 is a side elevational view of the safety plunger; and

,Fig. 5 is a horizontal sectional view showing the construction of the plunger.

Referring now to the drawing wherein there is shown a machine gun of the Browning type comprising a receiver Ill which includes a bottom plate l2 and a top plate l4. The breech end of the machine gun is provided with vertically disposed grooves l6 for receiving opposite tongues 18 provided on the back plate 20 which is assembled by a downward movement and supported by the bottom plate [2 in accordance with stand- I ard practice. The back plate 20 carries a buffer 22 which absorbs the energy of recoil of the breech bolt. A latch 24 is mounted within a slot 28 provided in the lower end of the back plate 20 and is supported therein by means of a pin 28 arranged as shown in Fig. 2. The nose 30 of the latch 24 is arranged to engage under the rear end ofthe bottom plate l2 as indicated in Fig. 2

ation of the latch. My improved safety means comprises a slidable bar element or plunger is which is arranged to be slidably supported within a transversely extending passage 42 provided di-.

rectly in the back plate 20. As indicated in Fig. 2, the bottom portion of the back plate is made thicker than the upper portion of the back plate in order to accommodate the plunger 40. The plunger 40 is limited in its movement by the removable pin 44 which passes through the slots 46 provided in the upper and lower walls of the plunger 40, as shown. The one end of the plunger 48 is hollowed out as indicated in Figs. 3, 4 and 5 so as to accommodate a coil spring 48 which serves the dual purpose of biasing the plunger 40 into safety position and to hold the stop pin 44 in assembled relationship. It will be observed that the stop pin 44 is provided with circumferential grooves 50 which cooperate with the outer convolution of the coil spring 48 in such a manner that the pin 44 is prevented from dropping out.

The back plate is provided with two holes 5'2 and 53, either one of which may be used for accommodating the pin 44 whereby the plunger may be mounted for operation from either side. As explained hereinabove, the pin 44 is held in place by means of the coil spring 48 with the result that the pin 44 may be removed by compressing the spring 48. Upon removal of the pin 44 from the hole 52, for example, the plunger 40 together with the spring 48 may be removed and inserted from the opposite end of the passage 42 and the pin 44 may be reassembled in the hole 53. The spring 48 may be compressed by inserting any convenient tool, such as a screw driver, in

through the open end of the cavity within which to clear the bottom plate l2. But, when the round portion of the plunger 40 is disposed above the latch 24, as shown in Fig. 3, it is impossible to The sides of the lunger release the latch 24. 40 are relieved or cut away at points 43 so as to provide clearance spring 32.

between the plunger and the 3 By virtue of the above described arrangement, it is apparent that any jarring of the gun during firing will have no tendency to cause the safety plunger 40 to move out of safety position, whereas with the prior art safety provided on the a present .50'caliber machine gun, the reciprocating movement of the gun during recoil tends to cause the safety to bounce out of safety position. Itis also apparent that the plunger is very conveniently located for engagement by the operators thumb as the operator grips the bufier 22 in the palm of the hand and operates the latch 24 with one of his other fingers.

-verse aperture therein adjacent said latch, said While the form of embodiment of the inven- I otall'y carried adjacent the lower portionof said back plate and arranged to engage the receiver to holdtlie back plate in place, spring means biasing said latch into latching position, a slid ablesafety element carried by said back plate for locking said latchin latching position, said back plate having a transverse aperture within whichlsaid safety element is slidably mounted, said-safety element comprising a plunger having ahollow portion, a spring disposed within said :back plate having a cutaway portion transversely intersecting said aperture providing clearance space sufficient to permit the unlatching movement of said latch, apin constituting a plunger slidably mounted within said transverse aperture, and spring means acting upon said plungerpin for biasing said pin to project a portion of said plunger pin into said clearanc space to prevent the unlatching of said latch, a stop means within said aperture stopping said pm when it projects apredetermineddistance into saidclearance space, a portion of one end of the plunger pinprotruding from said aperture to serve as an operating means to move the plunger pin out of the positionin which it prevents un- 1atching.-

5. In combination, a support, a latch carried by said support, said support having first and second passages arranged at right angles to one another, a slotted plunger operable in said first passage and having a portion movable into and out of looking, engagement with said latch a stoppi'n passingthrough said slotted plunger and arranged in: said second passage, and spring means having one end pushing against saidplunger and having the other end pushing a ainst the side of said pin, said pin having notched means within which the end of said spring rests so as to releasably hold the pin in place.

,6. In combination, a support, a latch carriedby said support, a hollow plunger slidably mounthollow portion, a pin carried by said back plate arranged in engagement with said last named space; said pin having groove means formed thereon in alignmentwith the convolutions of saidspring for en agement by said spring. L

2;.- In comb-ination, a support, a latch carried by said support, a safety for said latch comprising a plunger slidably mounted bysaid support and having a portion movable into andout o'flocking engagement'with said latch, a recess within said plunger, a coil spring Within said recess, and a stoppin carried by" said support and passing transversely through said plunger and said re c'ess, said pin having groove means formed thereon in engagenient'with the convolutions of said spring, said spring serving to hold said pin" against movement;

' 3. In a machine gun, a back plate of the type adapted to be slidably mounted i the receiver or agun by a lowering movement, a latch pivota-lly carried adjacent the lower portion of said back plate and arranged to engage the receiver to hold the back plate in place, spring means biasing said latch into latching position, said back plate including an; integral portion having a transverse aperture therein adjacent said latch, said back plate having a cutaway portion transversely intersecting said aperture providing clearance space sufii'cient to permit the unlatching movement of said latch, a pin constituting a plunger slidably mounted with-in said transverse aperture, and spring means acting upon said pl'u-nge'ir pin for biasing said pin to project a portion of said plunger pin into said clearance space to prevent the unlatching of said latch.

4. In a machine gun, a back plate of the type adapted to be slidably mounted in the receiver of a gun by a lowering movement, a latch pivotally carried adjacent the lower portion or said back plate and arranged to engage the receiver to hold the back plate i place, spring means biasing said latch into latching position, saidback plate including an integral portion having a trans ed in said support and having a portion movable into and out of locking engagement with said latch, a coil spring'disposed within the hollow of said plunger, a slot inone wall of said plunger, and a pin carried by said support and projecting through said slot and serving to limit the niov'emerit of said plunger, said pin having a circumsaid spring whereby said spring holds said pin in place, end of saidspring being accessible from one end of said hollow plunger whereby said spring may be compressed so as to disengage said pin,

7. In a machine gun, a back plate of the type adapted to be slidably mounted in the receiver of a gun by a lowering movement, a latch pivotally carried adjacent the lower portion of said back plate and arranged to engage the receiver to hold the back plate in place, means biasing said latch into latching position, said back plate having an integral portion projecting rearwardly therefrom and provided with a transversely extending aperture, a slidable safety element supported within said aperture with one end 1101- rnally projecting from said recess at one side of said integral projecting portion, said safety ele ment having a first portion which when lined up with said latch allows operation of the latch and having a second portion movable into alignment with said latch to lock said latch in latchirig position, said safety element having a spring receiving recess formed therein, a spring within said recess, a removable pin having at least one end engaged within a recess formed in said inte' gral projecting portion, said pin formingan abutment for said spring and also cooperating with said safety element to limit the movement thereof, said pin having a shoulder cooperating with said spring so as to rein'ovably h'old' said pin in place.

8'. In a machine gun, a b'ackplate of the type adapted to be slidably mounted the receiver of a'gun by a lowering movement, a latch 151w ferential groove arranged in engagement with otally carried adjacent the lower portion of said back plate and arranged to engage the receiver to hold the back plate in place, means biasing said latch into latching position, said back plate having an integral portion projecting rearwardly therefrom and provided with a transversely extending aperture, a slidable safety element supported within said aperture with one end normally projecting from said recess at one side of said integral projecting portion, said safety element having a first portion which when lined up with said latch allows operation of the latch and having a second portion movable into alignment with said latch to lock said latch in latching position, said safety element having a spring receiving recess formed therein, a spring within said recess, a removable pin having at least one end engaged within a recess formed in said integral projecting portion, said pin forming an abutment for said spring and also cooperating with said safety element to limit the movement thereof, said pin having a shoulder cooperating with said spring so as to removably hold said pin in place, said spring receiving recess having an opening through which said spring is accessible for moving the spring out of engagement with said pin whereby said pin may be removed.

9. In a machine gun, a back plate of the type adapted to be slidably mounted in the receiver of a gun by a lowering movement, a latch pivotally carried adjacent the lower portion of said back plate and arranged to engage the receive-r to hold the back plate in place, means biasing said latch into latching position, said back plate having an integral portion projecting rearwardly therefrom and provided with a transversely extending aperture, a slidable safety element supported within said aperture with one end normally projecting from said recess at one side of said integral projecting portion, said safety element having a first portion which when lined up with said latch allows operation of the latch and having a second portion movable into alignment with said latch to lock said latch in latching position, said safety element having a spring receiving recess formed therein, a spring within said recess, said slidable safety element being adapted to be inserted into said aperture from either side so as to be operable from either side, a pin for limiting movement of said element, said integral projecting portion having a pair of holes for selectively receiving said pin on either side of said latch, said pin having a shoulder cooperating with said spring so as to be removably held in place whereby said pin may be removed from one of said holes and said slidable safety element turned end for end and reassembled and held in place by the use of the same pin while located in a different hole.

LOUIS A. ANDERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,125,937 Benet et al Jan. 26, 1915 1,363,040 Hammond Dec. 21, 1920 1,913,840 Loomis June 13, 1933 2,335,854 Green Dec. 7, 1943 2,344,563 Punsalan Mar. 21, 1944 

